The present invention relates to an improved manner of placing registration marks in time cards for consecutive time clocks and sensing the registration marks to properly position the card for subsequent printings.
Time recorders (or "time clocks") have long been used by employers to record the hours worked by employees. Typically, each employee is given a card to be inserted into the time clock when beginning and ending a work period. The time of day is printed on the card each time the card is inserted in the time clock so that total elapsed time may be deduced from the successive printings.
In order for the time information recorded on the card to be intelligible, each printing must be displaced in some manner from previous printings. This may be done by moving the printing means relative to the card, or by maintaining the printing means in a fixed location while varying the position of the card relative to the printing means. Many time clocks employ the latter approach. Such clocks usually print time from the top of the card down, and are known as consecutive time clocks.
In consecutive time clocks, a circular hole is punched in the card at the same time the time of day is printed on the card. The hole is usually on the same line as the printing. On the next insertion of the card into the clock, this hole is used to sense the location of the last printing and to stop further insertion of the card to position the card for the next printing. This sequence of punch and stop continues down the card from printing to printing. The card material punched out with each printing is guided by a chute into a waste container where it is stored until it is discarded.
This approach has certain disadvantages. It requires a waste container for receiving material removed from the card and a chute for guiding the material to the container. The waste container must be emptied periodically. Individual pieces of punched-out material may become lodged in the machinery. Further, the card material between consecutive holes is weakened and is subject to tearing, which may cause loss of registration or cause the card to become jammed in the time clock.